Chapter 2
Using the Module
2-18
ni.com
Note
The ratio of the bridge output voltage and the excitation voltage is done internally
on the NI PXIe-4330/4331.
To convert module readings to strain use the following equation:
Force, Pressure, and Torque Sensor Configurations
The NI PXIe-4330/4331 can be used with force sensors (such as load cells), pressure sensors,
or torque sensors that have the following characteristics:
•
Wheatstone bridge based
1
•
Unamplified mV/V or V/V output
2
These sensors typically use a full-bridge configuration with a 350
Ω
nominal bridge
resistance, but other configurations and nominal bridge resistances can be used. Figure 2-17
shows the force, pressure, torque sensor circuit diagram.
Figure 2-17.
Force, Pressure, and Torque Sensor Circuit Diagram
1
Sensors that measure force, pressure, or torque through other means (for example, piezoelectric force sensors) cannot be used
with the NI PXIe-4330/4331.
2
Sensors that contain a built-in voltage or current amplifier cannot be used with the NI PXIe-4330/4331.
strain
ε
( )
2
–
V
r
GF
ν
1
+
(
)
V
r
ν
1
–
(
)
–
[
]
-----------------------------------------------------------
=
+
–
+
–
AI +
RS+
EX+
R
1
R
2
R
4
R
3
RS–
QTR
/SC
Shunt
Cal A
R
L
R
L
PXIe-4330/4331 Set Bridge
Configuration to Full Bridge
TB-4330
Transducer
V
CH
R
L
R
L
R
L
EX–
AI–
V
EX
R
S
